Community acquired pneumonia (CAP) is an important cause of morbidity and mortality in adults. It typically afflicts adults between the ages of 50 and 70, is the sixth most common cause of death in the United States and is the leading cause of infection-related deaths in the elderly. The objectives of this trial are to 1) demonstrate the safety and efficacy of once-daily therapy with gatifloxacin 400 mg. in the treatment of CAP requiring hospitalization and 2) compare the safety and efficacy of gatifloxacin 400mg. IV daily vs. ceftriaxone 1 or 2 gms. IV daily. This study is now closed to recruitment and in the data analysis phase.